Airless spray pump

ABSTRACT

An airless spray pump is provided with a single-acting piston pump which allows the use of a low-cost yoke drive. Motor and pump shaft are offset for most efficient force utilization.

This application claims benefit of Provisional Applications No.60/151,794 filed Aug. 31, 1999 and No. 60/166,946 filed Nov. 22, 1999.

TECHNICAL FIELD

Airless spray pumps for the spraying of paints and other coatings.

BACKGROUND ART

Airless spray pumps for the spraying of paints and other coatings viathe airless method are well known and have traditionally been dividedinto two types, diaphragm pumps for the lower end of the market andreciprocating piston pumps for the higher end.

DISCLOSURE OF THE INVENTION

An airless spray pump is provided with a single-acting piston pump whichallows the use of a low-cost yoke drive. Motor and pump shaft are offsetfor most efficient force utilization. The main drive housing has a motormounted to the rear thereof A gear assembly uses gear teeth which areformed with a 5° helical angle and have a 25° pressure angle. Thisgeometry combines the higher efficiency of straight cut gears with thenoise reduction typified in a helical design.

An eccentric is molded onto the front of the gear assembly and haslocated thereabout a bearing assembly which rides inside a yoke. Theyoke moves vertically on guide rods which are retained in pockets of thedrive housing. The yoke is molded of plastic as is the gear assemblyleading to lower cost and easier manufacture.

The pump rod is provided with a cap over the top end thereof which hasbearing. Pump assembly is designed as a single acting pump, that is, thepump only pumps on the downward stroke and loads on the upward stroke.This allows the components of the drive train, including the yoke andgear, to be much lighter as the yoke ends up being more of a guidancedevice rather than a force-applying device.

The motor and pinion are offset from the centerline of the pumpassembly. This arrangement does not have any significant cantileveringas the pump rod, pinion, yoke, eccentric and cap are all located in thesame plane. The location of the rod and the single acting pump withrespect to the gear centerline reduces the thrust loads on the yoke. Thelocation of the pinion on the gear partially offsets and reduces thepump forces on the gear shaft and bearings. By locating the eccentricbearing directly on the end of the pump rod cap which is press-fit iteliminates the transfer of pumping force through an intermediate membersuch as the yoke which provides longer life, efficiency and allows themanufacture of a more inexpensive yoke assembly.

The shaft packing assembly is comprised of a packing housing whichscrews into the pump housing and which contains a felt member which hasbeen soaked with throat seal lubricant or other solvent or lubricant. Astack of v-packings are compressed in place by wave spring which istightened by tightening the seal housing into the pump housing. Theinlet check is provided with a check ball and a check seat which ispressed into a check housing and which is held in place by a retainer.These parts all press-fit into one another such that the completeassembly be merely screwed into main pump housing for replacement.Similarly, outlet check assembly is formed of an outlet check housingwhich is screwed into a pump housing and similarly is provided with acheck ball held in place by a retainer. The outlet passageway is angledrelative to the axis of the pump shaft. This allows the outlet checkassembly to operate essentially via gravity and yet requires only thedrilling and provision of one passageway while maintaining anessentially vertical ball-seat relationship.

These and other objects and advantages of the invention will appear morefully from the following description made in conjunction with theaccompanying drawings wherein like reference characters refer to thesame or similar parts throughout the several views.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a prospective exploded view showing the airless spray pumpwith the instant invention.

FIG. 2 is a simple front plan view of the drive assembly and pump of theinstant invention.

FIG. 3 is a side plan view of the assembly shown in FIG. 1.

FIG. 4 is a detailed exploded view of the circled area in FIG. 3.

FIG. 5 is a cross-sectional view of the pump of the instant invention.

FIG. 6 shows more details of the drive assembly of the instantinvention.

FIG. 7 is another cross-sectional view of the pump portion of theinstant invention.

FIG. 8 is a cross-section of the outlet filter of the instant invention.

FIG. 9 is an exploded view of the outlet filter of the instantinvention.

FIG. 10 is a perspective exploded view of the instant invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The instant invention generally designated 10 is comprised of a maindrive housing 12 having a motor 14 mounted to the rear thereof. A gearassembly 16 having a rear bearing 17 and gear teeth 22 is inserted intothe bearing housing 20 of drive housing 12 to define gear centerline 41.Gear teeth 22 on gear assembly 16 mate with the teeth on pinion 24 onthe end of motor 14. The teeth 22 and on pinion 24 are formed with a 5°helical angle and have a 25° pressure angle. This geometry combines thehigher efficiency of straight cut gears with the noise reductiontypified in a helical design.

An eccentric 25 is also molded onto the front of gear assembly 16 andhas located thereabout a bearing assembly 28 which rides inside a yoke30. Yoke 30 moves vertically on guide rods 32 which are retained inpockets 34 of drive housing 12. Yoke 30 is molded of plastic. Gearassembly 16 is cast in ZA-12 with an integral counterweight leading tolower cost and easier manufacture.

Pump rod 36 is provided with a cap 38 over the top end thereof which hasbearing upon it bearing 28. Pump assembly 40 is designed as a singleacting pump that is the pump only pumps on the downward stroke and loadson the upward stroke. In doing so this allows the components of thedrive train, including the yoke and gear, to be much lighter as the yoke30 ends up being more of a guidance device rather than a force-applyingdevice.

As can be seen more particularly in FIG. 2, motor and pinion 24 areoffset from the centerline 42 of pump assembly 40 which also has offsettherefrom bearing 20 28 in the opposite direction. Also, thisarrangement does not have any significant cantilevering as the pump rod,pinion, yoke, eccentric and cap are all located in the same plane. Thelocation of the rod and the single acting pump with respect to the gearcenterline 41 reduces the thrust loads on the yoke. The location of thepinion on the gear partially offsets and reduces the pump forces on thegear shaft and bearings. By locating the eccentric bearing directly onthe end of the pump rod cap which is press-fit it eliminates thetransfer of pumping force through an intermediate member such as theyoke which provides longer life, efficiency and allows the manufactureof a more inexpensive yoke assembly.

The shaft packing assembly 44 shown in FIG. 4 is comprised of a packinghousing 46 which screws into pump housing 48 and which contains a feltmember 50 which has been soaked with throat seal lubricant or othersolvent or lubricant. A stack of v-packings 52 are compressed in placeby wave spring 54 which is tightened by tightening seal housing 46 intopump housing 48.

Turning to FIG. 7, inlet check 56 is provided with a check ball 58, acheck seat 60 which is pressed into check housing 62 and which is heldin place by retainer and integral ball guide 64. These parts allpress-fit into one another such that the complete assembly be merelyscrewed into main pump housing 48 for replacement. Similarly, outletcheck assembly 57 is formed of an outlet check housing 60 which isscrewed into pump housing 48 and similarly is provided with a check ball62 held in place by ball seat 65. As can also be seen in FIG. 7, theoutlet passageway 66 is angled relative to the axis of pump shaft 36.This allows the outlet check assembly 58 57 to operate essentially viagravity and yet requires only the drilling and provision of onepassageway while maintaining an essentially vertical ball-seatrelationship.

FIGS. 8 and 9 show the outlet filter assembly 80 which is comprised of afilter element 82 contained in passage 84 of pump assembly 40 and whichis retained by fitting 86.

Turning to FIG. 10, inlet tube 70 is provided with a female threaded end70a. Inlet filter screen assembly 72 has a male threaded end 72a forthreaded engagement with end 70a. Ends 70a and 72a use the same size andthread as a common garden hose such that a user need merely removescreen assembly 72, attach a garden hose to inlet tube 70, turn on thewater and flush out the assembly.

It is contemplated that various changes and modifications may be made tothe airless spray pump without departing from the spirit and scope ofthe invention as defined by the following claims.

1. A spray pump powered by a rotary motor having a pinion thereon and comprising: a housing; a single-acting piston pump having a pump rod and connected to said housing; a drive gear assembly comprising a gear rotatable about a gear centerline, and an eccentric located on said gear; a bearing located about said eccentric; and a yoke reciprocatingly located in said housing and about said bearing; wherein said gear centerline, motor and pinion are offset from the a centerline of said pump to reduce the thrust loads on the yoke and offset and reduce the pump forces.
 2. The spray pump of claim 1 wherein the teeth on said gear are formed with about a 5° helical angle and about a 25° pressure angle.
 3. The spray pump of claim 1 wherein said motor and pinion are offset from the centerline of said pump to reduce the thrust loads on the yoke and offset and reduce the pump forces is driven by said motor and engages teeth of said gear to rotate said gear and said eccentric about the gear centerline.
 4. An airless spray pump having an inlet tube and an inlet filter screen, the improvement comprising said inlet tube being provided with a female threaded end and said inlet filter screen assembly being provided with a male threaded end threaded engagement with female end, said ends having the same size and thread as a common garden hose such that a user need merely remove said screen assembly and attach a garden hose to said inlet tube to flush out the assembly.
 5. The spray pump of claim 1, wherein the single-acting piston pump pumps on a downward stroke of the pump rod and loads on an upward stroke of the pump rod.
 6. The spray pump of claim 5, wherein the pump rod is aligned with the centerline of the pump.
 7. The spray pump of claim 6, wherein the pump rod, yoke, and bearing are located in a common plane.
 8. The spray pump of claim 1, wherein the eccentric is integral with a front of the gear assembly.
 9. The spray pump of claim 1 and further comprising a motor mounted to a rear portion of the housing.
 10. The spray pump of claim 9, wherein the pinion is driven by the motor.
 11. A spray pump comprising: a rotary motor; a pinion driven by the rotary motor; a housing; a single-acting piston pump having a pump rod and connected to said housing wherein the single-acting piston pump pumps on a downward stroke of the pump rod and loads on an upward stroke of the pump rod, and wherein the pump rod is aligned with a centerline of the piston pump; a drive gear assembly comprising a gear driven by the pinion about a gear centerline, and an eccentric located on said gear; a bearing located about said eccentric; and a yoke reciprocatingly located in said housing and about said bearing so that rotation of the gear and the eccentric produce reciprocal motion of the yoke; wherein said gear centerline, motor and pinion are offset from the centerline of said pump to reduce the thrust loads on the yoke and offset and reduce the pump forces.
 12. The spray pump of claim 11, wherein the pump rod, yoke, and bearing are located in a common plane.
 13. The spray pump of claim 11, wherein the pump rod, yoke, eccentric, and bearing are located in a common plane.
 14. The spray pump of claim 11, wherein the eccentric is integral with a front of the gear assembly.
 15. The spray pump of claim 11 wherein the motor is mounted to a rear portion of the housing.
 16. The spray pump of claim 11, wherein the pinion includes teeth that engate teeth on an outer circumferential surface of the gear.
 17. The spray pump of claim 11, wherein said teeth on said gear and said pinion are formed with about a 5° helical angle and about a 25° pressure angle. 